1. Technical Field
This invention relates to a technology for printing an image by forming dots on a print medium.
2. Related Art
As an output device for images created by a computer, images shot using a digital camera, or the like, printing apparatuses that print images by forming dots on a print medium are widely used. Such a printing apparatus has tone values of dots which can be formed fewer than input tone values, and therefore expresses tone through halftone processing. The organizational dither method using a dither matrix is widely used as one of such halftone processing. The organizational dither method may have much effect on the image quality depending on the contents of the dither matrix, and therefore the dither matrix has been optimized by an analytical approach such as simulated annealing or genetic algorism using an evaluation function considering human vision as disclosed in JP-A-7-177351, JP-A-7-81190, and JP-A-1-329381, for example.
However, such optimization processing requires a complex computational algorism and huge amount of computation, and therefore there have remained difficult problems in possibility of processing for especially complex optimization problem.